score = int(input("请输入你的成绩："))
if score >= 90 and score <= 100:
    print("本次考试等级为A。")
elif score >= 80 and score < 90:
    print("本次考试等级为B.")
elif score >= 70 and score < 80:
    print("本次考试等级为C。")
elif score >= 60 and score < 70:
    print("本次考试等级为D。")
else:
    print("本次考试等级为E。")